Multilayer composite based on polyamide/polyolefin

ABSTRACT

Good adhesion between layers is achieved in a multilayer composite having the following layers:  
     I. a layer I of a polyamide molding composition;  
     II. a layer II of a bonding agent having at least 50% by weight of a mixture of  
     a) from 30 to 70 parts by volume of a polymer selected from  
     a polyamide and  
     a polyamine-polyamide copolymer,  
     b) from 0.1 to 70 parts by volume of an olefin polymer containing a functional group,  
     c) from 69.9 to 0 parts by volume of an unfunctionalized polyolefin, where the sum of the parts by volume of a), b) and c) is 100; and  
     III. a layer III of a polyolefin molding composition.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a multilayer composite in which apolyamide layer and a polyolefin layer are joined to one another by abonding agent.

[0003] 2. Discussion of the Background

[0004] Multilayer composites comprising a polyamide layer and apolyolefin layer are known per se. For example, DE-A 37 15 251 describesa two-layer tube consisting of a polyamide layer and a polyolefin layerfor conveying an alcoholic medium. To achieve any adhesion at allbetween the layers, the polyolefin contains groups derived from maleicacid.

[0005] DE-C 40 00 434 describes a multilayer coolant line which, in oneembodiment, comprises an outer polyamide layer, an inner polyolefinlayer and an intermediate bonding layer of a polyolefin bearingfunctional groups.

[0006] Such composites have firm adhesion between the layers after theirproduction. However, it has been found that adhesion between the layersof functionalized polyolefin and polyamide becomes lower and lower onprolonged contact with aqueous liquids or alcohol-containing fuel,particularly at elevated temperatures, and finally drops to values whichare no longer acceptable in practice. The reasons for this areconsidered to be alcoholysis or hydrolysis reactions.

[0007] A different concept is presented in U.S. Pat. No. 3,561,493.There, a mixture of polyamide and polyethylene is recommended as bondingagent between a polyamide layer and a polyolefin layer. However,attempts to reproduce this disclosure show that, depending on whichpolymer forms the coherent phase in the mixture, only adhesion either tothe polyamide layer or to the polyethylene layer is obtained, but neverboth at the same time.

[0008] Finally, EP-A-1 065 048, which is not a prior publication,describes a multilayer composite comprising a bonding agent whichcomprises a polyamine-polyamide copolymer. A polyolefin layer or thepresence of a polyolefin in the bonding agent is not disclosed there.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to produce a multilayercomposite comprising a polyamide layer and a polyolefin layer joined bya bonding layer which does not consist of a functionalized polyolefinalone.

[0010] It is another object to produce a multilayer composite in whichthe adhesion between layers remains largely intact even on prolongedcontact with alcohol-containing media or aqueous media at elevatedtemperatures.

[0011] This and other objects have been achieved by the presentinvention, the first embodiment of which includes a multilayercomposite, comprising:

[0012] the following layers bound directly to one another:

[0013] a layer I of a polyamide molding composition;

[0014] a layer II of a bonding agent comprising at least 50% by weightof a mixture of

[0015] a) from 30 to 70 parts by volume of a polymer selected from thegroup consisting of a polyamide, a polyamine-polyamide copolymer and acombination thereof;

[0016]  wherein said polyamine-polyamide copolymer is prepared using thefollowing monomers:

[0017] α) from 0.1 to 25% by weight, based on the polyamine-polyamidecopolymer, of a polyamine containing at least 3 nitrogen atoms, and

[0018] β) a polyamide-forming monomer selected from the group consistingof a lactam; a ω-aminocarboxylic acid; an equimolar combination of adiamine and a dicarboxylic acid; and a mixture thereof,

[0019] b) from 0.1 to 70 parts by volume of an olefin polymer containinga functional group,

[0020] c) from 69.9 to O parts by volume of an unfunctionalizedpolyolefin,

[0021] wherein the sum of the parts by volume of a), b) and c) is 100;and

[0022] a layer III of a polyolefin molding composition.

[0023] Another embodiment of the present invention includes a moldingcomposition, comprising:

[0024] at least 50% by weight of the following components:

[0025] a) from 30 to 70 parts by volume of a polymer selected from thegroup consisting of a polyamide, at least 0.1 part by volume ofpolyamine-polyamide copolymer and a combination of a polyamide and atleast 0.1 part by volume of polyamine-polyamide copolymer;

[0026]  wherein said polyamine-polyamide copolymer is prepared using thefollowing monomers:

[0027] α) from 0.1 to 25% by weight, based on the polyamine-polyamidecopolymer, of a polyamine containing at least 3 nitrogen atoms, and

[0028] β) a polyamide-forming monomer selected from the group consistingof a lactam; a ω-amino carboxylic acid; an equimolar combination of adiamine and a dicarboxylic acid; and a mixture thereof,

[0029] b) from 0.1 to 70 parts by volume of an olefin polymer containinga functional group,

[0030] c) from 69.9 to 0 parts by volume of an unfunctionalizedpolyolefin,

[0031] wherein the sum of the parts by volume of, a), b) and c) is 100.

DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention relates to a multilayer composite whichcomprises the following layers bound directly to one another:

[0033] I. a layer I of a polyamide molding composition;

[0034] II. a layer II of a bonding agent comprising at least 50% byweight, preferably at least 70% by weight and particularly preferably atleast 90% by weight, of a mixture of

[0035] a) from 30 to 70 parts by volume of a polymer selected from thegroup consisting of a polyamide, a branched polyamine-polyamidecopolymer and a combination of a polyamide and a branchedpolyamine-polyamide copolymer;

[0036]  wherein said branched polyamine-polyamide copolymer is preparedusing the following monomers:

[0037] α) from 0.1 to 25% by weight, preferably from 0.5 to 20% byweight and particularly preferably from 1 to 16% by weight, based on thepolyamine-polyamide copolymer, of a polyamine containing at least 3,preferably at least 4, particularly preferably at least 8 and veryparticularly preferably at least 11 nitrogen atoms, and having a numberaverage molecular weight of preferably at least 146 g/mol, particularlypreferably at least 500 g/mol and very particularly preferably at least800 g/mol, and

[0038] β) a polyamide-forming monomer selected from the group consistingof a lactam, ω-aminocarboxylic acid and/or an equimolar combination ofdiamine and dicarboxylic acid,

[0039] b) from 0.1 to 70 parts by volume of an olefin polymer containinga functional group,

[0040] c) from 69.9 to 0 parts by volume of an unfunctionalizedpolyolefin,

[0041] wherein the sum of the parts by volume of a), b) and c) is 100;and

[0042] III. a layer III of a polyolefin molding composition.

[0043] The amount of component a) in layer II is preferably 30 to 70parts by volume, more preferably 40 to 60 parts by volume. The amount ofcomponent a) includes all values and subvalues therebetween, especiallyincluding 35, 40, 45, 50, 55, 60 and 65 parts by volume.

[0044] The amount of component b) in layer II is preferably 0.1 to 70parts by volume. The amount of component b) includes all values andsubvalues therebetween especially including 0.5, 1, 5, 10, 15, 20, 25,30, 35, 40, 45, 50, 55, 60 and 65 parts by volume.

[0045] The amount of component c) in layer II is preferably 69.9 to 0parts by volume. The amount of component c) includes all values andsubvalues therebetween, especially including 69, 68, 67, 66, 65, 60, 55,50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 3 and 1 parts by volume.

[0046] The amount of the polyamide α) in component a) of layer II ispreferably 0.1 to 25% by weight. The amount of polyamine α) includes allvalues and subvalues therebetween, especially including 0.5, 1, 2, 3, 5,10, 15 and 20% by weight.

[0047] Preferred polyamides for the layer I or the bonding agent arefirst and foremost aliphatic homopolycondensates and copolycondensates,for example PA 4B, PA 66, PA 68, PA 612, PA 88, PA 810, PA 1010, PA1012, PA 1212, PA 6, PA 7, PA 8, PA 9, PA 10, PA 11 and PA 12. Thedesignation of the polyamides corresponds to the international standard,where the first digit(s) indicates the number of carbon atoms in thestarting diamine and the last digit(s) indicates the number of carbonatoms of the dicarboxylic acid. If only one number is given, this meansthat the polyamide has been prepared from an α,ω-aminocarboxylic acid orfrom the lactam derived therefrom. For further information, referencemay be made to H. Domininghaus, Die Kunststoffe and ihre Eigenschaften,pages 272 ff., VDI-Verlag, 1976.

[0048] If copolyamides are used, they can comprise, for example, adipicacid, sebacic acid, suberic acid, isophthalic acid, terephthalic acid,naphthalene-2,6-dicarboxylic acid, etc., as coacid andbis(4-aminocyclohexyl)methane, trimethylhexamethylenediamine,hexamethylenediamine or the like as codiamine. Lactams such ascaprolactam or laurolactam or aminocarboxylic acids such asω-aminoundecanoic acid can likewise be incorporated as cocomponents.

[0049] The preparation of these polyamides is known (e.g. D. B. Jacobs,J. Zimmermann, Polymerization Processes, pp. 424-467, IntersciencePublishers, New York, 1977; DE-B 21 52 194).

[0050] Further preferred polyamides are mixed aliphatic/aromaticpolycondensates as are described, for example, in U.S. Pat. No.2,071,250, No. 2,071,251, No. 2,130,623, No. 2,130,943, No. 2,241,322,No. 2,312,966, No. 2,512,606 and No. 3,393,210 and also in Kirk-Othmer,Encyclopedia of Chemical Technology, 3rd edition, Vol. 18, pages 328 ff.and 435 ff., Wiley & Sons, 1982. Other preferred polyamides arepoly(ether ester amides) or poly(ether amides). Such products aredescribed, for example, in DE-A 25 23 991, DE-A 27 12 987 and DE-A 30 06961.

[0051] The polyamide molding composition can comprise either one ofthese polyamides or a mixture of a plurality of them. Up to 40% byweight of other thermoplastics can also be present, as long as they donot interfere with the bonding capability. Particularly preferredexamples of such further thermoplastics are impact-toughening rubberssuch as ethylene-propylene or ethylene-propylene-diene copolymers (EPA-0295 076), polypentenylene, polyoctenylene, random or block copolymers ofalkenylaromatic compounds with aliphatic olefins or dienes (EP-A-0 261748) or core/shell rubbers having a tough elastic core of(meth)acrylate, butadiene or styrene-butadiene rubber having a glasstransition temperature Tg of ←10° C., where the core may be crosslinkedand the shell may be made up of styrene and/or methyl methacrylateand/or further unsaturated monomers (DE-As 21 44 528, 37 28 685).

[0052] The polyolefin of layer III or of the bonding agent is, forexample, polyethylene or polypropylene. It is in principle possible touse any commercial type of polyolefin. Thus, for example, possiblepolyolefins are: linear polyethylene of high, intermediate or lowdensity, LDPE, isotactic or atactic homopolypropylene, random copolymersof propene with ethane and/or 1-butene, ethylene-propylene blockcopolymers and the like. The polyolefin can further comprise animpact-toughening component such as EPM or EPDM rubber or SEBS.Furthermore, the customary auxiliaries and additives may also bepresent. The polyolefin can be prepared by any known process, forexample by the Ziegler-Natta process, by the Phillips process, by meansof metallocenes or by a free-radical process.

[0053] The molding composition of layer III may be crosslinked asdescribed in the prior art so as to achieve an improvement in themechanical properties, e.g. the cold impact toughness, the heatdistortion resistance or the creep behavior, or in the permeability.Crosslinking is carried out, for example, by radiation crosslinking orby moisture crosslinking of polyolefin molding compositions containingsilane groups.

[0054] The bonding agent of layer II may further comprise, in additionto the mixture of the components a), b) and c), another polymer or acustomary auxiliary and/or additive, as long as these do notsignificantly impair the bonding action.

[0055] Examples of functional groups which may be present in the olefinpolymer of component II.b) are acid anhydride groups, N-acyllactamgroups, carboxylic acid groups, epoxide groups, oxazoline groups,trialkoxysilane groups and hydroxyl groups. The functional groups can beintroduced either by copolymerization of a suitable monomer togetherwith the olefin or by a grafting reaction. In the case of the graftingreaction, a preformed polyolefin is reacted in a known manner with anunsaturated, functional monomer and advantageously a free-radical sourceat elevated temperature.

[0056] The olefin polymers or polyolefins of components b) and c) can beidentical or different. For example, it is possible to use anethylene-propylene rubber functionalized with maleic anhydride groups ascomponent b) and an unfunctionalized isotactic homopolypropylene ascomponent c).

[0057] In a preferred embodiment, the bonding agent contains at least0.1 part by volume of the polyamine-polyamide copolymer and particularlypreferably at least 0.5 part by volume. In a further preferredembodiment, the amino group concentration of the polyamine-polyamidecopolymer is in the range from 100 to 2500 mmol/kg. The amino groupconcentration includes all values and subvalues therebetween, especiallyincluding 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200,1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300 and2400 mmol/kg. As polyamine, it is possible to use, for example,substances from the following classes:

[0058] polyvinylamines (Rompp Chemie Lexikon, 9th edition, Volume 6,page 4921, Georg Thieme Verlag, Stuttgart 1992);

[0059] polyamines which are prepared from alternating polyketones (DE-A196 54 058);

[0060] dendrimers such as

[0061] ((H₂N—(CH₂)₃)₂N—(CH₂)₃)₂—N(CH₂)₂N((CR₂)₂N((CH₂)₃—NH₂)₂)₂

[0062] (DE-A-196 54 179) or

[0063] tris(2-aminoethyl)amine,N,N-bis(2-aminoethyl)-N′,N′-bis[2-[bis(2aminoethyl)amino]ethyl]-1,2-ethanediamine,

[0064]3,15-bis(2-aminoethyl)-6,12-bis[2-[bis(2-aminoethyl)aminolethyl]-9[bis[2-bis(2-aminoethyl)amino]ethyl]amino]ethyl]-3,6,9,12,15-pentaazaheptadecane-1,17-diamine (J. M. Warakomski, Chem, Mat. 1992, 4, 1000-1004);

[0065] linear polyethylenimines which can be prepared by polymerizationof 4,5-dihydro-1,3-oxazoles and subsequent hydrolysis (HoubenWeyl,Methoden der Organischen Chemie, Volume E20, pages 1482-'1487, GeorgThieme Verlag, Stuttgart, 1987);

[0066] branched polyethylenimines which are obtainable by polymerizationof amidines (Houben-Weyl, Methoden der Organischen Chemie, Volume E20,pages 1482-1487, Georg Thieme Verlag, Stuttgart, 1987) and generallyhave the following amino group distribution:

[0067] from 25 to 46% of primary amino groups,

[0068] from 30 to 45% of secondary amino groups and

[0069] from 16 to 40% of tertiary amino groups.

[0070] In the preferred case, the polyamine has a number averagemolecular weight M_(n) of not more than 20,000 g/mol, particularlypreferably not more than 10,000 g/mol and very particularly preferablynot more than 5000 g/mol.

[0071] Lactams or ω-aminocarboxylic acids used as polyamide-formingmonomers contain from 4 to 19, in particular from 6 to 12, carbon atoms.The number of carbon atoms includes all values and subvaluestherebetween, especially including 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17 and 18 carbon atoms. Particular preference is given to usingε-caprolactam, ε-aminocaproic acid, caprylolactam, ω-aminocaprylic acid,laurolactam, ω-aminododecanoic acid and/or ω-aminoundecanoic acid.

[0072] Examples of combinations of diamine and dicarboxylic acid arehexamethylenediamine/adipic acid, hexamethylenediamine/dodecanedioicacid, octamethylenediamine/sebacic acid, decamethylenediamine/sebacicacid, decamethyienediamine/dodecanedioic acid,dodecamethylenediamine/dodecanedioic acid anddodecamethylenediamine/2,6-naphthalenedicarboxylic acid. However, it isalso possible to use all other combinations, for example decamethylenediamine/dodecanedioic acid/terephthalic acid,hexamethylenediamineladipic acid/terephthalic acid,hexamethylenediamineladipic acid/caprolactam,decamethylenediamine/dodecanedioic acid/ω-aminoundecanoic acid,decamethylenediamine/dodecanedioic acid/laurolactam,decamethylenediamine/terephthalic acid/laurolactam ordodecamethylenediamine/2,6-naphthalenedicarboxylic acid/laurolactam.

[0073] In a preferred embodiment, the polyamine-polyamide copolymer isprepared using, in addition, an oligocarboxylic acid selected from thegroup consisting of from 0.015 to about 3 mol % of dicarboxylic acid andfrom 0.01 to about 1.2 mol % of tricarboxylic acid, in each case basedon the sum of the other polyamide-forming monomers. In this ratio,diamine and dicarboxylic acid in the equivalent combination of thesemonomers are each regarded individually. The amount of dicarboxylic acidincludes all values and subvalues therebetween, especially including0.02, 0.05, 0.08, 0.11, 0.14, 0.17, 0.2; 0.25; 0.3; 0.35; 0.4; 0.5; 0.6;0.7; 0.8; 0.9; 1.0; 1.1; 1,2; 1,3; 1,4; 1,5; 1.6; 1.7; 1.8; 1.9; 2.0;2.1; 2.2; 2.3; 2.4; 2.5; 2.6; 2.7; 2.8; and 2.9 mol %. The amount oftricarboxylic acid include all values and subvalues therebetween,especially including 0.02; 0.05; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.8; 0.9;1.0 and 1.1 mol %. If a dicarboxylic acid is used, preference is givento adding from 0.03 to 2.2 mol %, particularly preferably from 0.05 to1.5 mol %, very particularly preferably from 0.1 to 1 mol % and inparticular from 0.15 to 0.65 mol %; if a tricarboxylic acid is used,then preference is given to adding from 0.02 to 0.9 mol %, particularlypreferably from 0.025 to 0.6 mol %, very particularly preferably from0.03 to 0.4 mol % and in particular from 0.04 to 0.25 mol %. The use ofthe oligocarboxylic acid significantly improves the solvent and fuelresistance, in particular the hydrolysis and alcoholysis resistance.

[0074] As oligocarboxylic acid, it is possible to use any dicarboxylicor tricarboxylic acid having from 6 to 24 carbon atoms, for exampleadipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioicacid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,cyclohexane-1,4-dicarboxylic acid, trimesic acid and/or trimelliticacid.

[0075] In addition, aliphatic, alicyclic, aromatic, araliphatic and/oralkylaryl-substituted monocarboxylic acids having from 3 to 50 carbonatoms, e.g. lauric acid, unsaturated fatty acids, acrylic acid orbenzoic acid, can, if desired, be used as regulators. These regulatorsenable the concentration of amino groups to be reduced without alteringthe molecular structure. Furthermore, functional groups such as doubleor triple bonds, etc., can be introduced in this way. However, it isdesirable for the polyaminepolyamide copolymer to have a substantialproportion of amino groups. The amino group concentration of thecopolymer is preferably in the range from 150 to 1500 mmol/kg,particularly preferably in the range from 250 to 1300 mmol/kg and veryparticularly preferably in the range from 300 to 1100 mmol/kg. The aminogroup concentration of the copolymer includes all values and subvaluestherebetween, especially including 200, 300, 400, 500, 600, 700, 800,900, 1000, 1100, 1200, 1300 and 1400 mmol/kg. Here and in the following,the term: amino groups refers not only to terminal amino groups but alsoto any secondary or tertiary amine functions present in the polyamine.

[0076] In the polyamine-polyamide copolymer, the composition of thepolyamide part can vary within a very wide range since the compatibilitywith the polyamide of the layer I is obviously determined by otherfactors and is generally given.

[0077] The polyamine-polyamide copolymers can be prepared by variousmethods.

[0078] One possibility is to combine the polyamide-forming monomers andthe polyamine and then carry out the polymerization or polycondensation.The oligocarboxylic acid can be added either at the beginning or duringthe reaction.

[0079] However, a preferred method is a two-stage process in whichlactam cleavage and the prepolymerization may firstly be carried out inthe presence of water (as an alternative, the correspondingω-aminocarboxylic acids or diamines and dicarboxylic acids are useddirectly and prepolymerized), after which the polyamine is added in thesecond step, while any oligocarboxylic acid is introduced before, duringor after the prepolymerization. The reaction mixture is thendepressurized at temperatures of from 200 to 290° C. andpolycondensation is carried out in a stream of nitrogen or under reducedpressure. The temperature includes all values and subvaluestherebetween, especially including 210, 220, 230, 240, 250, 260, 270 and280° C.

[0080] A further preferred method is hydrolytic degradation of apolyamide to form a prepolymer and simultaneous or subsequent reactionwith the polyamine. Preference is given to using polyamides in which theend group difference is approximately zero or in which anyoligocarboxylic acid has already been incorporated by polycondensation.However, the oligocarboxylic acid can also be added at the beginning ofor during the degradation reaction.

[0081] These processes make it possible to prepare ultra highly branchedpolyamides having acid numbers of less than 40 mmol/kg, preferably lessthan 20 mmol/kg and particularly preferably less than 10 mmol/kg. Areaction time of from one to five hours at temperatures of from 200° C.to 290° C. is sufficient to achieve almost complete conversion.

[0082] If desired, a reduced pressure phase of a number of hours canfollow in a further process step. This has a duration of at least fourhours, preferably at least six hours and particularly preferably atleast eight hours, at from 200 to 290° C. The temperature includes allvalues and subvalues therebetween, especially including 210, 220, 230,240, 250, 260, 270 and 280° C. After an induction period of a number ofhours, an increase in the melt viscosity is observed, which may beattributable to a reaction of amino end groups with one another takingplace with elimination of ammonia and chain formation. This furtherincreases the molecular weight, which is advantageous for extrusioncompositions in particular.

[0083] If the reaction is not to be carried out to completion in themelt, the polyamine-polyamide copolymer can also be after-condensed inthe solid phase.

[0084] The multilayer composite of the invention may further compriseadditional layers besides the layers I, II and III, provided that theseadditional layers adhere to the other layers. Possible additional layersare first and foremost layers having a good barrier action in respect tofuel components, water, alcohols, glycols or gases. These layersconsist, in particular, of a molding composition based on athermoplastic polyester (e.g. polybutylene terephthalate, polyethylene2,6-naphthalate, polybutylene 2,6-naphthalate), a fluorinated polymer(e.g. polyvinylidene fluoride, ETFE or THV), an ethylene-vinyl alcoholcopolymer (EVOH) or polyoxymethylene.

[0085] The molding compositions of layers I, II and III may furthercomprise up to 50% by weight of additives selected fromimpact-toughening rubber and/or a customary auxiliary and an additive.

[0086] Impact-toughening rubbers for polyamide molding compositionscontain functional groups derived from unsaturated functional compoundswhich are either copolymerized into the main chain or are grafted ontothe main chain. Most useful is EPM or EPDM rubber onto which maleicanhydride has been grafted by a free-radical mechanism. Such rubbers canalso be used together with an unfunctionalized polyolefin such asisotactic polypropylene, as described in EP-A-0 6883 290.

[0087] The molding compositions may also contain relatively smallamounts of auxiliaries and additives which are necessary for obtainingparticular properties. Preferred examples are plasticizers, pigments orfillers such as carbon black, titanium dioxide, zinc sulfide, silicatesor carbonates, processing aids such as waxes, zinc stearate or calciumstearate, flame retardants such as magnesium hydroxide, aluminum,hydroxide or melamine cyanurate, glass fibers, antioxidants, UVstabilizers and additives which give the product antielectrostaticproperties or electric conductivity, e.g. carbon fibers, graphitefibrils, fibers of stainless steel or conductive carbon black.

[0088] In one possible embodiment, the molding compositions contain from1 to 25% by weight of plasticizers, particularly preferably from 2 to20% by weight and very particularly preferably from 3 to 15% by weight.The amount of plasticizers includes all values and subvaluestherebetween, especially including 2, 3, 4, 5, 7, 9, 11, 13, 15, 17, 19,21 and 23% by weight.

[0089] Plasticizers and their use in polyamides are known. A generalreview of plasticizers suitable for polyamides may be found inGachter/Muller, Kunststoffadditive, C. Hanser Verlag, 2nd edition, p.296.

[0090] Preferred compounds suitable as plasticizers are, for example,esters of phydroxybenzoic acid having from 2 to 20 carbon atoms in thealcohol component or amides of arylsulfonic acids having from 2 to 12carbon atoms in the amine component, more preferably amides ofbenzenesulfonic acid.

[0091] Particularly preferred plasticizers include ethylp-hydroxybenzoate, octyl p-hydroxybenzoate, i-hexadecylp-hydroxybenzoate, N-n-octyltoluenesulfonamide,N-n-butylbenzenesulfonamide or N-2 ethylhexylbenzenesulfonamide.

[0092] The multilayer composite of the invention is, in one embodiment,a pipe, a filling port or a container, in particular for conveying orstoring liquids or gases, for example in motor vehicles. Such a pipe canbe straight or corrugated or have only some corrugated sections.Corrugated pipes are known (e.g. U.S. Pat. No. 5,460,771), so thatfurther details are superfluous. Important applications of suchmultilayer composites are fuel lines, tank filling ports, vapor lines(i.e. lines in which fuel vapors are conveyed, e.g. breather pipes),filling station pipes, coolant lines, pipes in air conditioning units,lines for clutch fluid, air brake lines, lines for windscreen washers orfuel containers.

[0093] The multilayer composite of the invention can also be in the formof a flat composite, for example as a film, such as a packaging film forfoodstuffs.

[0094] When the multilayer composite of the invention is used forconveying or toning combustible liquids, gases or dusts, e.g. fuel orfuel vapor, it is advisable to make one of the layers of the compositeor an additional interior layer electrically conductive. This can beachieved by compounding with an electrically conductive additive bymeans of all methods of the prior art. As conductive additive, it ispossible to use, for example, conductive carbon black, metal flakes,metal powder, metallized glass spheres, metallized glass fibers, metalfibers (for example of stainless steel), metallized whiskers, carbonfibers (including metallized carbon fibers), intrinsically conductivepolymers, e.g. polyaniline, or graphite fibrils. Mixtures of variousconductive additives can also be used.

[0095] The electrically conductive layer is preferably in direct contactwith the medium to be conveyed or stored and has a surface resistance ofnot none than 109 Q/square, preferably not more than 10⁹ Ω/square. Themethod of determining the resistance of multilayer pipes is described inSAE J 2280 (November 1996, paragraph 7.9).

[0096] When the multilayer composite of the invention is configured as ahollow body or hollow profile (e.g. a pipe), this can be additionallysheathed with a further elastomer layer. Suitable sheathing materialsinclude both crosslinking rubber compositions and thermoplasticelastomers. The sheathing can be applied to the pipe either with orwithout the use of an additional bonding agent, for example by extrusionvia a crossflow head or by pushing a prefabricated elastomer hose overthe finished, extruded multilayer pipe.

[0097] Examples of preferred elastomers are chloroprene rubber,ethylenepropylene rubber (EPM), ethylene-propylene-diene rubber (EPDM),epichlorohydrin rubber (EGO), chlorinated polyethylene, acrylate rubber,chlorosulfonated polyethylene, silicone rubber, plasticized PVC,polyether ester amides or polyether amides.

[0098] The muitilayer composite can be manufactured in one or morestages, for example by a single-stage process using multicomponentinjection molding, coextrusion or coextrusion blow molding, or bymultistage processes as described, for example, in U.S. Pat. No.5,554,425.

[0099] To increase the bursting strength, the composite can furthercomprise a reinforcing textile layer.

[0100] The invention also provides the molding compositions of the layerII described here. These can be used not only for the multilayercomposite of the invention but also on their own for molded parts of anytype.

[0101] Having generally described this invention, a furtherunderstanding can be obtained by reference to certain specific exampleswhich are provided herein for purposes of illustration only, and are notintended to be limiting unless otherwise specified.

EXAMPLES

[0102] Preparation of a Polyamine-polyamide Copolymer:

[0103] 4.78 kg of laurolactam were melted at from 180 to 210C in amelting vessel and transferred to a pressure-rated polycondensationvessel 250 ml of water and 57 ppm of hypophosphorous acid were thenadded. The cleavage of the laurolactam was carried out at 280° C. underautogenous pressure. The vessel was subsequently depressurized over aperiod of 3 hours to the vapor pressure of residual water of 3 bar and230 g of polyethylenimine (LUPASOLO® 100, BASF AG, Ludwigshafen) wereadded. The mixture was then depressurized to atmospheric pressure andpolycondensation was carried out at 250° C. for 2 hours while passingnitrogen over the reaction mixture. The clear melt was discharged as anextruded strand by means of a melt pump, cooled in a water bath andsubsequently granulated.

[0104] The copolymer obtained had a polyethylenimine content of 4.5% byweight and a PA12 content of 95.5% by weight.

Example 1

[0105] 45 parts by weight of VESTAMID® ZA7295 (a high-viscosity PA12 forextrusion molding compositions containing an excess of terminal aminogroups), 40 parts by weight of NOVOLEN® 2500H (an ethylene-propyleneblock copolymer from Targor GmbH; extrusion grade), 10 parts by weightof ADMER® Q520E (an isotactic polypropylene grafted with maleicanhydride from Mitsui) and 5 parts by weight of the polyamine-polyamidecopolymer prepared above were melted and mixed at 250° C. for 5 minutesin a laboratory kneader from Haake.

[0106] A 2 mm thick sheet was produced from the resulting compound bypressing at 250° C. In a similar way, 4 mm thick sheets were producedboth from VESTAMID® ZA7295 and from NOVOLEN® 2500H by pressing at 240°C.

[0107] Subsequently, the following sheets (from the bottom to the top)were placed in the sheet press:

[0108] NOVOLEN® 2500H

[0109] Compound

[0110] VESTAMID® ZA7295.

[0111] The upper part of the press had a temperature of 240° C., whilethe lower part had a temperature of 200° C. The pressing time was 5minutes.

[0112] Adhesion Test:

[0113] Neither the PA12 layer nor the PP layer could be detached fromthe compound by hand. When a great deal of force was applied, thecomposite failed instead by rupture of the compound.

Example 2

[0114] 45 parts by weight of VESTAMID® ZA7295, 40 parts by weight ofNOVOLEN® 2500H, 10 parts by weight of KRATON® FG 1901X (an SEBS graftedwith maleic anhydride from Shell) and 5 parts by weight of thepolyamine-polyamide copolymer prepared above were melted and mixed at250° C. for 5 minutes in a laboratory kneader from Haake.

[0115] A 2 mm thick sheet was produced from the resulting compound bypressing at 250° C. In a similar way, 4 mm thick sheets were producedboth from VESTAMID® ZA7295 and from NOVOLEN® 2500H by pressing at 240°C. The sheets were then pressed together as in Example 1.

[0116] Adhesion Test:

[0117] As in Example 1, neither the PA12 layer nor the PP layer could bedetached from the compound by hand. When a great deal of force wasapplied, the composite failed instead by rupture of the compound.

[0118] German patent application 10065177.1 filed Dec. 23, 2000, isincorporated herein by reference.

[0119] Obviously, numerous modifications and variations on the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A multilayer composite, comprising: the following layers bounddirectly to one another: a layer I of a polyamide molding composition; alayer II of a bonding agent comprising at least 50% by weight of amixture of a) from 30 to 70 parts by volume of a polymer selected fromthe group consisting of a polyamide, a polyamine-polyamide copolymer anda combination thereof;  wherein said polyamine-polyamide copolymer isprepared using the following monomers: α) from 0.1 to 25% by weight,based on the polyamine-polyamide copolymer, of a polyamine containing atleast 3 nitrogen atoms, and β) a polyamide-forming monomer selected fromthe group consisting of a lactam; a ω-aminocarboxylic acid; an equimolarcombination of a diamine and a dicarboxylic acid; and a mixture thereof,b) from 0.1 to 70 parts by volume of an olefin polymer containing afunctional group, c) from 69.9 to 0 parts by volume of anunfunctionalized polyolefin, wherein the sum of the parts by volume ofa), b) and c) is 100; and a layer III of a polyolefin moldingcomposition.
 2. The multilayer composite as claimed in claim 1, whereincomponent a) in layer II contains at least 0.1 part by volume of thepolyamine-polyamide copolymer.
 3. The multilayer composite as claimed inclaim 1, wherein component a) in layer II contains at least 0.5 part byvolume of the polyamine-polyamide copolymer.
 4. The multilayer compositeas claimed in claim 1, wherein the polyamine-polyamide copolymer isprepared using from 0.5 to 20% by weight of the polyamine.
 5. Themultilayer composite as claimed in claim 1, wherein thepolyamine-polyamide copolymer is prepared using from 1 to 16% by weightof the polyamine.
 6. The multilayer composite as claimed in claim 1,wherein the polyamine contains at least 4 nitrogen atoms.
 7. Themultilayer composite as claimed in claim 1, wherein the polyaminecontains at least 8 nitrogen atoms.
 8. The multilayer composite asclaimed in claim 1, wherein the polyamine contains at least 11 nitrogenatoms.
 9. The multilayer composite as claimed in claim 1, wherein thepolyamine has a number average molecular weight M_(n) of at least 146g/mol.
 10. The multilayer composite as claimed in claim 1, wherein thepolyamine has a number average molecular weight M_(n) of at least 500g/mol.
 11. The multilayer composite as claimed in claim 1, wherein thepolyamine has a number average molecular weight M_(n) of at least 800g/ml.
 12. The multilayer composite as claimed in claim 1, wherein anamino group concentration of the polyamine-polyamide copolymer is in therange from 100 to 2500 mmol/kg.
 13. The multilayer composite as claimedin claim 1, wherein the functional group of the olefin polymer is anacid anhydride group, a N-acyllactam group, a carboxylic acid group, anepoxide group, an oxazoline group, a trialkoxysilane group or a hydroxylgroup.
 14. The multilayer composite as claimed in claim 1, wherein oneof the layers I, II or III or an additional interior layer has been madeelectrically conductive.
 15. The multilayer composite as claimed inclaim 1, which is in the form of a pipe.
 16. The multilayer composite asclaimed in claim 15, which is fully or partially corrugated.
 17. Themultilayer composite as claimed in claim 1, which is in the form of ahollow body.
 18. The multilayer composite as claimed in claim 15,wherein the outermost layer is adjoined by an additional elastomerlayer.
 19. The multilayer composite as claimed in claim 1, which is inthe form of a fuel line, a tank filling port, a vapor line, a fillingstation pipe, a station pipe, a coolant line, a pipe in an airconditioning unit, a line for clutch fluid, an air brake line, awindscreen washer pipe or a fuel container.
 20. The multilayer compositeas claimed in claim 1, which is in the form of a film.
 21. A moldingcomposition, comprising: at least 50% by weight of the followingcomponents: a) from 30 to 70 parts by volume of a polymer selected fromthe group consisting of a polyamide, at least 0.1 part by volume ofpolyamine-polyamide copolymer and a combination of a polyamide and atleast 0.1 part by volume of polyamine-polyamide copolymer;  wherein saidpolyamine-polyamide copolymer is prepared using the following monomers:α) from 0.1 to 25% by weight, based on the polyamine-polyamidecopolymer, of a polyamine containing at least 3 nitrogen atoms, and β) apolyamide-forming monomer selected from the group consisting of alactam; a ω-aminocarboxylic acid; an equimolar combination of a diamineand a dicarboxylic acid; and a mixture thereof, b) from 0.1 to 70 partsby volume of an olefin polymer containing a functional group, c) from69.9 to 0 parts by volume of an unfunctionalized polyolefin, wherein thesum of the parts by volume of, a), b) and c) is 100.